d_to_q, q_to_d

src/diffpy/utils/transforms.py

@@ -16,9 +16,7 @@
     "The supplied q-array and wavelength will result in an impossible two-theta. "
     "Please check these values and re-instantiate the DiffractionObject with correct values."
 )
-invalid_input_emsg = (
-    "Input values have resulted in an infinite output. Please ensure there are no zeros in the input."
-)
+inf_output_msg = "WARNING: The largest output is infinite and cannot be plotted."
 
 
 def _validate_inputs(q, wavelength):
@@ -61,7 +59,6 @@ def q_to_tth(q, wavelength):
     -------
     tth : 1D array
         The array of :math:`2\theta` values in degrees numpy.array([tths]).
-        This is the correct format for loading into diffpy.utils.DiffractionObject.on_tth.
     """
     _validate_inputs(q, wavelength)
     q.astype(float)
@@ -107,7 +104,6 @@ def tth_to_q(tth, wavelength):
     q : 1D array
         The array of :math:`q` values np.array([qs]).
         The units for the q-values are the inverse of the units of the provided wavelength.
-        This is the correct format for loading into diffpy.utils.DiffractionObject.on_q.
     """
     tth.astype(float)
     if np.any(np.deg2rad(tth) > np.pi):
@@ -138,8 +134,8 @@ def q_to_d(q):
         The array of :math:`d` values np.array([ds]).
     """
     if 0 in q:
-        raise ValueError(invalid_input_emsg)
-    return 2.0 * np.pi / copy(q)[::-1]
+        warnings.warn(inf_output_msg)
+    return 2.0 * np.pi / copy(q)
 
 
 def tth_to_d(ttharray, wavelength):
@@ -163,8 +159,8 @@ def d_to_q(d):
         The units of q must be reciprocal of the units of wavelength.
     """
     if 0 in d:
-        raise ValueError(invalid_input_emsg)
-    return 2.0 * np.pi / copy(d)[::-1]
+        warnings.warn(inf_output_msg)
+    return 2.0 * np.pi / copy(d)
 
 
 def d_to_tth(darray, wavelength):

tests/test_transforms.py

@@ -103,8 +103,8 @@ def test_tth_to_q_bad(inputs, expected):
     ([np.array([])], np.array([])),
     # UC2: User specified valid q values
     (
-        [np.array([np.pi / 6, 1 * np.pi, 2 * np.pi, 3 * np.pi, 4 * np.pi, 5 * np.pi])],
-        np.array([0.4, 0.5, 0.66667, 1, 2, 12]),
+        [np.array([5 * np.pi, 4 * np.pi, 3 * np.pi, 2 * np.pi, np.pi, 0])],
+        np.array([0.4, 0.5, 0.66667, 1, 2, np.inf]),
     ),
 ]
 
@@ -115,31 +115,13 @@ def test_q_to_d(inputs, expected):
     assert np.allclose(actual, expected)
 
 
-params_q_to_d_bad = [
-    # UC1: user specified an invalid q value that results in an infinite d value
-    (
-        [np.array([0, 1, 2, 3, 4])],
-        [
-            ValueError,
-            "Input values have resulted in an infinite output. Please ensure there are no zeros in the input.",
-        ],
-    ),
-]
-
-
-@pytest.mark.parametrize("inputs, expected", params_q_to_d_bad)
-def test_q_to_d_bad(inputs, expected):
-    with pytest.raises(expected[0], match=expected[1]):
-        q_to_d(inputs[0])
-
-
 params_d_to_q = [
     # UC1: User specified empty d values
     ([np.array([])], np.array([])),
     # UC2: User specified valid d values
     (
-        [np.array([np.pi / 6, 1 * np.pi, 2 * np.pi, 3 * np.pi, 4 * np.pi, 5 * np.pi])],
-        np.array([0.4, 0.5, 0.66667, 1, 2, 12]),
+        [np.array([0, 1 * np.pi, 2 * np.pi, 3 * np.pi, 4 * np.pi, 5 * np.pi])],
+        np.array([np.inf, 2, 1, 0.66667, 0.5, 0.4]),
     ),
 ]
 
@@ -148,21 +130,3 @@ def test_q_to_d_bad(inputs, expected):
 def test_d_to_q(inputs, expected):
     actual = d_to_q(inputs[0])
     assert np.allclose(actual, expected)
-
-
-params_d_to_q_bad = [
-    # UC1: user specified an invalid d value that results in an infinite q value
-    (
-        [np.array([0, 1, 2, 3, 4])],
-        [
-            ValueError,
-            "Input values have resulted in an infinite output. Please ensure there are no zeros in the input.",
-        ],
-    ),
-]
-
-
-@pytest.mark.parametrize("inputs, expected", params_d_to_q_bad)
-def test_d_to_q_bad(inputs, expected):
-    with pytest.raises(expected[0], match=expected[1]):
-        d_to_q(inputs[0])